ALEXANDER VON HU1MBOLBT. 123 tally and in layers, and resting on clay-slate., whose layers were partly perpendicular, partly in an angle of 85 degrees. This was a highly-important fact for Hurnboldt in his theory of the formation of granite. When he had again arrived at the abovenamed fortress, he proceeded thence through the steppe of X&chirn, which belongs to the -central tribe of Khir- gises, to the southern portion of the TTral chain; he crossed the line of the Qossacks of Ischim over Semi- piatinsk and Omsk, and arrived at Mjask. From here, frequent excursions were made into the vicinity. On a district of inconsiderable extent, and only a few inches below the sxirface, three pieces of pure gold were found, of which two weighed 28 and the third 43^- marks (18 and 28 pounds). The course of the southern Ural was followed as far as Orsk, where the remarkable quarries of green jasper attracted Huin- boldt's attention, and where his geological studies found abundant scope in the river Jaik3 which crosses the mountain-ridge in a north-western direc- tion, Humboklt now turned his course to Orenburg,* where he arrived by the road over Guberlinsk, on the 21st September. Here in Orenburg, where caravans of many thousand camels arrive yearly, Humboldt made the acquaintance of a certain Herr von Gens, who was a very intelligent man, and interested him- self particularly for the geography of Asia, for which he had collected a quantity of important materials. He had travelled far, and Humboldt gained many useful explanations and descriptions from him. Among others, he learned of a high mountain, which had once been a volcano, and which still disturbs the passing caravans by storms which it is said to occa- sion, and whose anger the inhabitants propitiate by sacrifices of sheep, situated to the north-east of tiste great Balkasch lake, which receives the waters of the river Sli. Gens had this communication from a Tartar, Orenburg lies below the level of the sea.